scholarly journals BER Analysis Using Beat Probability Method of 3D Optical CDMA Networks with Double Balanced Detection

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Chih-Ta Yen ◽  
Chih-Ming Chen
Keyword(s):  
System Performance ◽  
Multiple Access ◽  
Three Dimensional ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Probability Method ◽  
Detection Mechanism ◽  
Cdma Networks ◽  
Balanced Detection ◽  
Code Division Multiple

This study proposes novel three-dimensional (3D) matrices of wavelength/time/spatial code for code-division multiple-access (OCDMA) networks, with a double balanced detection mechanism. We construct 3D carrier-hopping prime/modified prime (CHP/MP) codes by extending a two-dimensional (2D) CHP code integrated with a one-dimensional (1D) MP code. The corresponding coder/decoder pairs were based on fiber Bragg gratings (FBGs) and tunable optical delay lines integrated with splitters/combiners. System performance was enhanced by the low cross correlation properties of the 3D code designed to avoid the beat noise phenomenon. The CHP/MP code cardinality increased significantly compared to the CHP code under the same bit error rate (BER). The results indicate that the 3D code method can enhance system performance because both the beating terms and multiple-access interference (MAI) were reduced by the double balanced detection mechanism. Additionally, the optical component can also be relaxed for high transmission scenery.

Performance Analysis of 2-D Prime Codes Encoded Optical CDMA System

2019 ◽  
Vol 40 (4) ◽  
pp. 463-472
Author(s):  
Ankita Rani ◽  
Deepak Kedia
Keyword(s):  
Multiple Access ◽  
Electrical Power ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Wavelength Division ◽  
High Data ◽  
Construction Methods ◽  
Data Rates ◽  
Improved Performance ◽  
Code Division Multiple

Abstract Optical code division multiple access (OCDMA) system provides highly secured transmission in addition to its capabilities to support asynchronous transmission and soft blocking. Two-dimensional OCDMA codes are chosen in this paper due to their high cardinality, good spectral efficiency and flexibility in their construction methods against direct sequence codes. This paper focuses on study of impact of multiple access interference (MAI) at high data rates for 2-D prime codesbased OCDMA system. It is shown that how the change in number of simultaneous users affects the transmission quality. Further, performance of the system is analysed in terms of bit error rate, received electrical power and eye openings. In addition, this paper also shows a comparative analysis of 2-D codes-based OCDMA system and wavelength division multiple access (WDMA) system in order to justify the improved performance of the proposed system. It is observed that the performance of 2-D OCDMA system is much better than WDMA system in terms of quality as well as security.

Unified KS-Code

2009 ◽  
pp. 1473-1479 ◽  
Author(s):  
M. K.A. Abdullah ◽  
S. A. Aljunid ◽  
M. D.A. Samad ◽  
S. B.A. Anas ◽  
R. K.Z. Sahbudin
Keyword(s):  
Multiple Access ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Service Guarantees ◽  
Narrow Bandwidth ◽  
Network Topologies ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Many codes have been proposed for optical CDMA system as discussed in Svetislav, Mari, Zoran, Kosti, and Titlebaum (1993), Salehi (1989), Liu and Tsao (2002), Maric, Moreno, and Corrada (1996), Wei and Ghafouri-Shiraz (2002), and Prucnal, Santoro, and Ting (1986). Optical code division multiple access (OCDMA) has been recognized as one of the most important technologies for supporting many users in shared media simultaneous, and in some cases can increase the transmission capacity of an optical fiber. OCDMA is an exciting developments in short haul optical networking because it can support both wide and narrow bandwidth applications on the same network, it connects large number of asynchronous users with low latency and jitter, and permits quality of service guarantees to be managed at the physical layer, offers robust signal security and has simplified network topologies. However, for improperly designed codes, the maximum number of simultaneous users and the performance of the system can be seriously limited by the multiple access interference (MAI) or crosstalk from other users. Another issue in OCDMA is how the coding is implemented. The beginning idea of OCDMA was restricted in time domain, in which the encoding/decoding could not been fully utilized in optical domain. Therefore a new coding in OCDMA has been introduced based on spectral encoding (Kavehrad & Zaccarin, 1995; Pearce & Aazhang, 1994; Smith, Blaikie, & Taylor, 1998; Wei & Ghafouri-Shiraz, 2002). The system, called Optical Spectrum CDMA, or OS-CDMA, has the advantage of using inexpensive optical sources, and simple direct detection receivers. In this article with an emphasis on the Spectral Amplitude Coding scheme, a new code known as Khazani-Syed (KS) code is introduced.

scholarly journals An Efficient Method to Reduce an MAI’s Effect in Spectral Amplitude Coding OCDMA Network

2017 ◽  
Vol 2 (6) ◽  
pp. 1
Author(s):  
Kamal Elsiddig Amaseb ◽  
Hassan Yousif Ahmed ◽  
Medien Zeghid
Keyword(s):  
Optical Communication ◽  
System Performance ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Integer Number ◽  
Quadratic Congruence ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Multiple access interference (MAI) in spectral-amplitude coding, optical code division multiple access (SAC-OCDMA) scheme hardly limits the system performance. This problem increases proportionally with the amount of concurrent users. In addition, phase induces intensity noise (PIIN) coming from the spontaneous emission process of light source is extra impairment leads to system drop needs to be tackled too. Towards overcome the specified problems, vector combinatorial (VC) codes which based on grouping of certain vectors is proposed. Any positive integer number can be used in both weighs and user parameters in code building procedure, these technique nominees our code to be a potential reliable applicant for future optical communication schemes. Such flexibility is an exceptional property for VC compared to SAC-OCDMA counterparts’ codes. Compared with the systems employing Hadamard, Modified Frequency Hopping (MFH), Modified Quadratic-Congruence (MQC), and Modified Double Weight (MDW), numerical results show that, the VC is effective to reduce the power of MAI and PIIN. It has been exposed that, performance can be superior significantly when VC is used.

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

2014 ◽  
Vol 35 (4) ◽  
Author(s):  
N. Alsowaidi ◽  
T. Eltaif ◽  
M. R. Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Successive Interference Cancellation ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Cdma System ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractDue to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase–induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

A Review on Successive Interference Cancellation-Based Optical PPM-CDMA Signaling

2017 ◽  
Vol 38 (1) ◽  
Author(s):  
Naif Alsowaidi ◽  
Tawfig Eltaif ◽  
Mohd Ridzuan Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Successive Interference Cancellation ◽  
Optical Cdma ◽  
Quadratic Congruence ◽  
Random Location ◽  
High Intensity Signal ◽  
Code Division Multiple ◽  
The Impact

AbstractThis paper presents a comprehensive review of successive interference cancellation (SIC) scheme using pulse position modulation (PPM) for optical code division multiple access (OCDMA) systems. SIC scheme focuses on high-intensity signal, which will be selected after all users were detected, and then it will be subtracted from the overall received signal, hence, generating a new received signal. This process continues till all users eliminated one by one have been detected. It is shown that the random location of the sequences due to PPM encoding can reduce the probability of concentrated buildup of the pulse overlap in any one-slot time, and support SIC to easily remove the effect of the strongest signal at each stage of the cancellation process. The system bit error rate (BER) performance with modified quadratic congruence (MQC) codes used as signature sequence has been investigated. A detailed theoretical analysis of proposed system taking into account the impact of imperfect interference cancellation, the loss produced from the splitting during encoding and decoding, the channel loss and multiple access interference is presented. Results show that under average effective power constraint optical CDMA system using SIC scheme with

A Study of Modified Prime Codes Optical CDMA for Wired-Wireless System

2013 ◽  
Vol 284-287 ◽  
pp. 2672-2676
Author(s):  
Chih Ta Yen ◽  
Wen Bin Chen
Keyword(s):  
Multiple Access ◽  
Multiple Access Interference ◽  
Base Station ◽  
Optical Cdma ◽  
Intensity Noise ◽  
Cost System ◽  
Spectral Coding ◽  
Code Division Multiple ◽  
Arrayed Waveguide ◽  
Prime Codes

In this study, we propose optical code-division multiple-access (OCDMA) network for the radio-over-fiber (RoF) transmissions. The network encoder/decoders (codecs) are structured on the basis of arrayed-waveguide-grating (AWG) routers coded with modified prime codes (MPCs). Performances are numerically evaluated with the effect of phase-induced-intensity-noise (PIIN). It showed that the new code families with lower cross correlation can suppress the intensity noise and cancel out the multiple-access interference (MAI) in balanced detection process effectively and hence improve the system performance. By the proposed MPC-coded OCDMA ROF network codecs, each network requires only two AWG routers to accomplish spectral coding of radio base station (RBS) and decoding of control station (CS), thus, resulting in a simpler and lower cost system. It is possible to accomplish interference- and crosstalk-free optical CDMA system for RoF transmissions.

A Review on Spectral Amplitude Coding Optical Code Division Multiple Access

2017 ◽  
Vol 38 (1) ◽  
Author(s):  
Navpreet Kaur ◽  
Rakesh Goyal ◽  
Monika Rani
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Noise Source ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Correlation Property ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractThis manuscript deals with analysis of Spectral Amplitude Coding Optical Code Division Multiple Access (SACOCDMA) system. The major noise source in optical CDMA is co-channel interference from other users known as multiple access interference (MAI). The system performance in terms of bit error rate (BER) degrades as a result of increased MAI. It is perceived that number of users and type of codes used for optical system directly decide the performance of system. MAI can be restricted by efficient designing of optical codes and implementing them with unique architecture to accommodate more number of users. Hence, it is a necessity to design a technique like spectral direct detection (SDD) technique with modified double weight code, which can provide better cardinality and good correlation property.

PERFORMANCE ANALYSIS OF SEVERAL QUASI-ORTHOGONAL CODES OPTICAL CDMA FOR RADIO-OVER-FIBER SYSTEM

2013 ◽  
Vol 37 (3) ◽  
pp. 415-426
Author(s):  
Chih-Ta Yen ◽  
Ing-Jr Ding ◽  
Cheng-Mu Tsai
Keyword(s):  
Multiple Access ◽  
Cross Correlation ◽  
Low Cost ◽  
Multiple Access Interference ◽  
Radio Over Fiber ◽  
Base Stations ◽  
Optical Cdma ◽  
Fiber System ◽  
Spectral Coding ◽  
Code Division Multiple

An optical code-division multiple-access (OCDMA) network for radio-over-fiber (RoF) transmissions was proposed. The network encoders/decoders (codecs) were structured based on arrayed-waveguide-grating (AWG) routers coded using modified prime codes (MPCs). In the proposed system, the lower in-phase cross correlation could reduce the beating noise, and in the proposed study, its performance was compared with that of a conventional system that uses M-sequence and Walsh-Hadamard codes. The performance of both systems was numerically evaluated by analyzing the effect of phase-induced-intensity noise (PIIN). The results showed that the new code families that had lower cross correlation can suppress the intensity of the noise and effectively cancel out the multiple-access interference (MAI) in balanced detection processes, which improved system performance. By using the proposed MPC-coded OCDMA ROF network codecs, each network required only two AWG routers to accomplish the spectral coding of radio base stations (RBSs) and the decoding of control stations (CSs), resulting in a simple and low-cost system. Therefore, it is possible to produce interference- and crosstalk-free optical CDMA systems for RoF transmissions.

scholarly journals ACO-Based Multi-User Detection in Cooperative CDMA Networks

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Ali Jafarnia Jahromi ◽  
Mohammad T. Abdizadeh
Keyword(s):  
Computational Complexity ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Cooperative Diversity ◽  
Multiple Access Interference ◽  
Base Station ◽  
Relay Nodes ◽  
Cdma Networks ◽  
Code Division Multiple ◽  
Detector Simulation

In this paper, the cooperative diversity is investigated in the uplink of a Code Division Multiple Access (CDMA) network in which users cooperate by relaying each other’s messages toward the Base Station (BS). It is assumed that the spreading waveforms are not orthogonal and hence, Multiple Access Interference (MAI) exists at the relay nodes as well as the BS. MAI degrades the signal quality at both relays and BS and decreases the cooperative diversity gain. To alleviate this problem, an Ant Colony Optimization (ACO) based Multi-User Detector (MUD) has been proposed to efficiently combine the received signals from the direct and relay paths and sub-optimally extract transmitted bits at the BS. The computational complexity of proposed algorithm is significantly lower than that of the Maximum Likelihood (ML) detector. More explicitly, for a cooperative network supporting 15 users, the computational complexity of the proposed ACO algorithm is a factor of 103 lower than that of the optimum Bayesian detector. Simulation results show that the performance of the proposed ACO-based detector can closely approach the maximum diversity in terms of BER and efficiently cancel the MAI at the BS.

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